Recent studies have shown that drug abusers who participate regularly scheduled, brief assessment and counseling sessions significantly reduce their drug use and related behaviors, including their risk of HIV infection. Though these changes have been observed for 3-12 months following an intervention, the persistence of effects beyond 12 months has not been well evaluated. This project will take advantage of a natural experiment in which IDUs were involved in a longitudinal study of HIV risk behavior and seroincidence. In this project we refer to these assessment and counseling sessions as low threshold-low intensity drug counseling (LT-LI). LT-LI counseling consists of regular, semi-annual contacts during which participants receive drug and risk reduction counseling, comprehensive evaluation of their drug use and related problems and HIV testing and counseling. The design of this project will capitalize upon an opportunity to conduct a natural experiment to test the impact of LT-LI among 300 IDUs. Subjects for this investigation will be derived from well- characterized cohorts of IDUs who participated in the NIDA funded Risk Assessment Project (RAP). The RAP was a longitudinal study of risk behaviors and HIV infection among IDUs in Philadelphia. It began in 1989, added a second cohort in 1992 and continued through the spring 1997. During the study period, significant reductions in drug use were observed among participants. These reductions were associated with reductions in drug related risk behaviors and reduced infections with HIV. We believe that the counseling services provided to the study participants were a key casual factor in the observed rates of reduced drug use and related behaviors. This study will attempt to re-engage all of the living and locatable 348 subjects who were evaluated at the last followup point during the Spring of 1997. Based on past experience, we estimate that 300 will be available and willing to be re-engaged. Subjects will be randomly selected, divided into two groups, and recruited in two waves of 150 each separated by one year. LT-LI sessions will be repeated every six months during the study period. Our primary hypotheses are that drug use prevelance and frequency will have increased since the last counseling, but that it will again decrease in association with re-enrollment in LT-LI. If successful, this study will provide new information about the persistence of reductions in drug use and related behaviors associated with a brief intervention, and will also provide valuable data on the long-term course of risk behavior, treatment involvement, psychiatric symptoms, mortality and HIV disease progression among IDUs. We also believe this model of intervention has important public health significance as a sustainable, community based, early intervention for drug users.